JCtx

There's a HUGE difference inside the car (as expected), and that's not going to get any better. Thank you for posting that. Guess will keep my stock exhaust... unless a good valved system that looks OEM (not slanted mufflers, etc) with the best of both worlds comes along.

rjmalm

One needs to put the measured values in the context of tire noise as well.
I was sitting still when I made the JoeZ measurements. Tire noise can be
80-84dB easy (measure while coasting). So one can compare tire road noise to the windows up 82 dB max and mid 70dB in the low rpm to 2500 rpm that I measured while the car was not moving. This allows low noise street driving if you can keep your throttle controlled and road trip driving where you shift up and also use the lower rpm range around town when you want to be quiet. (< 5dB difference in these areas and sometime lower). 3dB difference is barely perceptible.
But for you a valved system might work better. Too bad other vendors with values dont publish the difference in dB for Open and Partial Closed.

I love the JoeZ sound addition when I want it. I should make some measurements on the road and some pass by test like the track sound checks at full throttle but I would rather just drive and enjoy.

I will upload the in cab windows up video to YouTube for you.

JCtx

Thanks a lot man. But an iPhone app might not be the best way to determine that. Did you notice as you revved the engine, noise was substantially louder, but your iPhone started showing lower and lower numbers after 3K rpm or so? Anyway, thought those measurements were on the road, but are too low for that indeed. So forget about my comment. Without road and wind noise in the mix, stationary numbers are utterly useless indeed. Wish you had done the interior measurement on the freeway before switching, but too late for that now. He he. Thanks anyway.

rjmalm

Yes it was only to add some numbers to JoeZ videos that only showed sound and RPM.

I did take some OEM readings, windows up on the freeway before the change but no video of the meter. Just had my wife write them down: 45mph on rough pavement 82db, 65mph hwy 303 slotted concrete 82db, 55mph on older pavement 79db, 75mph on older pavement 82.5 to 86.2 with meter set to slow (average filter) and on fast response it was going from 80db to 91.85. On newer pavement with the fast meter setting I got from 81db to 86db. Sometime I will repeat with JoeZ for you.
None of the above freeway samples except the ramp reading we in the
max dB range of 3000 rpm. Wish I would have done videos of these tests.
Freeway ramp, full throttle 2nd gear to 3rd 92.9dB max.

I also did some videos/audio of OEM and JoeZ exhaust sound with the iphone placed 50ft from the drive line at constant rpm as I passed by:
rpm,OEM,JoeZ 2k,65,79 3k,66,78 4k,72,79 5k,76,82

JCtx

[QUOTE=rjmalm;9224761Someday will repeat with JoeZ mod.[/QUOTE]
Awesome; thanks a lot. That should be a good enough comparison. Plus your comments (and maybe your wife's) on how noticeable the measured difference really is. I'm worried about my wife if I ever change the exhaust again, not me, by the way. Thanks again brother.

rjmalm

My wife and I captured about 20-30 videos of the dB meter and translated the dB values to a plot for you. These numbers were measured when running on flat pavement areas. Small hills required added throttle and dB would increase from 5 to 8 db but I did not plot those. Road differences caused 4-5 dB and I tried to record numbers on about the same texture.

I tried to drive the tests on the smooth roads. I did not go back to the exact same place for the slower speeds since you were more interested in road trip speeds, too far to drive.

I did do one run up from 10mph to 100 on a freeway entrance ramp and plotted a few points for that. Oh, the blue curve: I would just shift to neutral and coast and take the readings of the wind and tire noise. I will PM you and dropbox the videos.

Also did a short shift run up from 1st 2nd to 3rd from a stop and plotted some values. Had 1 old run up in 2nd and added it as well. The average
and peak values have quite a range. Again I will dropbox the videos if you want.

I also re did the plot at every 100rpm vs 500 and the peaks do not follow the average curve shape. Example pics shows the average was 91.6db at 4k in 2nd but you can see the analog meter has already dropped to 86db. The higher average was due to the 95db during 2.5krpm range of the 1st gear run.

I also measured the back seat vs front seat and found about 5-7dB louder in the back. Dropbox will have the videos.

Also did the standard track test. Meter placed 50 ft from the drive line and did a full throttle run by the meter. Shift from 1st to 2nd
was about 75ft before the meter (78dB) and then 85dB directly in front of the meter (closest distance) and as revs were approaching red line after
pass in the meter the peak value went to about 98dB with average at 96dB. Video is crappy but usable.

rjmalm

JoeZ, I reran some dB measures after 1900miles. In park, idle to 4k.
Some reductions. Not sure what the measurement error might be. My guess is + - 1 dB, With engine off I measured 34-37dB.
See image.

Also did a MAX AC fan on measurement and got 68dB when it was max on, and 65db with fan off.

Joe Z

iTrader: (10)

As expected a reduction in levels due to materials burning in

Thank you for sharing all your findings once again.!!

Joe Z

johnnyreb

WOW, rj i can Only imagine What your Wife has to put up with!